code: def test_compute_test_value(self):
      x = T.scalar("x")
      x.tag.test_value = np.array(1.0, dtype=config.floatX)
      op = OpFromGraph([x], [x**3])
      y = T.scalar("y")
      y.tag.test_value = np.array(1.0, dtype=config.floatX)
      f = op(y)
      grad_f = T.grad(f, y)
      assert grad_f.tag.test_value is not None
  
imports: from __future__ import absolute_import, print_function, division
  from functools import partial
  import numpy
  import theano
  from theano import config, shared
  from theano.gradient import DisconnectedType
  from theano.gof.null_type import NullType
  from theano.compile import function
  from theano import tensor
  from theano.tensor.shared_randomstreams import RandomStreams
  from theano.compile.builders import OpFromGraph
  from theano.tests import unittest_tools
label_desc: Use image node_id 15 for calling the T_OpFromGraph obj's underlying member method code with example usage: obj.test_compute_test_value() without return types